" A SUMMARY OF BRAIN TRAINING FUELING GUIDELINES • Drink only when you’re thirsty during running. But don’t allow your thirst to build—that is, drink as soon as you feel the urge and as often as you feel the urge. Never force yourself to drink more than is comfortable. • Drink during runs lasting longer than one hour and during the recovery periods in shorter, high-intensity interval workouts. • When performance counts, use a sports drink instead of water. Its electrolyte content enhances hydration and its carbohydrate content provides an extra source of energy and stimulates a brain signal that boosts performance. • Consider using a carbohydrate-protein sports drink (Accelerade) instead of a conventional sports drink to promote faster recovery from workouts and perhaps greater long-term fitness gains. • Consider using water or an electrolyte-fortified water instead of a sports drink during some of your long runs to increase the physiological stress of these runs in ways that will enhance your body’s adaptations to them. "

― Matt Fitzgerald , Brain Training For Runners: A Revolutionary New Training System to Improve Endurance, Speed, Health, and Results